Methyl aryl silicones and insulated conductors and other products utilizing the same



Oct 1941- E. G. ROCHOW 2,258,222

CUA/DZICTUR INSULATION COMPR/S/IVG POLYMER/C METHYL HRYL S/L/CUNECONDUCTOR Inventor: Eugene G. Rochow,

His: Abbot-n83.

UNITED STATES PATENT OFFICE METHYL ARYL SILICONES AND INSULATEDCONDUCTORS AND OTHER. PRODUCTS UTILIZING THE SAME Eugene G. Rochow, WestAlbany, N. Y., assignor to General Electric Company, a corporation ofNew York Application April 27, 1940, Serial No. 332,099

27 Claims.

The present invention relates to new compositions of matter and, moreparticularly, to compositions comprising new and useful methyl arylsilicones. The scope of the invention also includes products whereinthese new compositions are utilized, for example insulated electricalconductors comprising a metallic conductor and insulation thereoncomprising the new compositions of this invention. This application is acontinuation-in-part of my copending applications Serial No. 287,787,filed August 1, 1939, and Serial No. 296,819, filed September 27, 1939,both of which applications are assigned to the same assignee as thepresent invention.

In the chemical literature, the name silicone" is given to compounds ofthe general formula which are tolyl, xylyl, mono-, diand tri-ethylphenyls, mono-, diand tri-propyl phenyls, etc.; naphthyl, monoandpoly-alkyl naphthyls, e. g., methyl naphthyl, diethyl naphthyl,tripropyl naphthyl, etc.; tetrahydronaphthyl; anthracyl;

and the halogenated derivatives of such radicals, more particularly thechloro, fluoro, bromo and a iodo derivatives of such radicals. Hence theand their polymers, where R and R are the same or different alkyl oraryl radicals or any other organic radicals capable of direct union withthe silicon atom.

With reference to the above formula, the products of this invention arethose in which R. is a methyl radical and R is a halogenated ornonhalogenated aryl radical; or, in polymeric form, products having theunit structure,

where A is any aryl radical, halogenated or nonhalogenated.

In my copending application Serial No. 287,787 I showed the productionof methyl silicones and defined such compounds in that application aschemical compounds composed essentially of silicon, oxygen and at leastone methyl group attached directly to silicon.

In my copending application Serial No. 296,819 I disclosed thepreparation of new and useful silicones in which either or both R and Rin the above formula are halogenated aryl radicals. When only one of thegroupings is a halogenated aryl radical, the other may be an alkyl,aryl, aralkyl or other non-haiogen-containing grouping capable of beingattached directly to silicon. Examples of such halogenated silicones areditrichlorophenyl) silicone, di- (monobromophenyl) silicone,di-(monochlorotolyl) silicone, methyl trichlorophenyl silicone, etc.However, no spechic claims were made in application Serial No.

silicones of the present invention include not only methyl arylsilicones, but also methyl halo-aryl silicones, e. g., methylchlorophenyl silicone.

Any suitable method may be used in preparing the new silicones of thisinvention, the choice of the method being determined largely by theyield obtained. For example, these new chemical compounds may beprepared by hydrolyzing a mass containing a compound having the formulaA-SLX| where A is an aryl (halogenated or non-halogenated) radical and Xis a halogen atom, specifically a chlorine atom. The hydrolyzed productis dehydrated to form the corresponding silicone at normal (room)temperature, or more rapidly at elevated temperatures, and underatmospheric or subatmospheric pressure condi-,

(2) The clear ether solution was decanted from the solid magnesiumsalts. The methyl phenyl magnesium dichloride contained in th s ethersolution was hydrolyzed by pouring the cold solution upon cracked ice:

(3) The resulting hydroxy compounds or silicols were washed with waterto remove excess acid, after which they were partly condensed tosilicones by distilling of! the ether and a part of the water. Theresulting partial condensation products are insoluble in water, butsoluble in organic solvents, e. g., benzene, toluene, etc.

Toluene was added to the ether-tree mass and the solution boiled slowlyfor several hours to I distill oiI more water of condensation, leaving a(A) CH: CH:

[ to is.

(4) The product or the preceding step may be polymerized or condensedfurther by additional heat treatment. For example, it may be polymerizedin thin layers by heating for 30 minutes at 120 C. to remove the solvent(toluene), followed by further heating at about 150 to 225 C., e. g.,for 15 to 25 minutes at 175 C. Thicker layers require a longer time, say3 hours at 175 1, a cyclic trimer; etc.

C. The resulting polymer is tough, strong, nonsticlgv, softens with heatbut does not liquefy, and has no odor when cold. It represents acombination in one material oi! the properties or the thermo-setting,high-silicon-content methyl silicone with the properties of theoxidation-resistant aryl silicones, It is an excellent binder material,effectively wetting and bonding together masses of glass fibers. Ananalysis of this composition shows it to correspond with the formula(CsHs) 0.5:(CH3) o.'19SiOi.19(OH) 0.10

Further heating makes the resin harder by continued condensation.Samples of glass cloth treated with the less highly polymerized resinand then allowed to condense further in situ showed no cracking of theresin-or any visual evidence of deterioration after one month at 175 C.

In the methyl aryl silicones of this invention the methyl and arylgroups may be attached to any or all of the silicon atoms in themolecule, or one methyl group may be attached to one silicon atom andone aryl group to another silicon atom. Ordinarily the polymericsilicone will have in its molecule an average of about one to not morethan two total methyl and aryl groups, more particularly methyl andphenyl groups, per silicon atom; that is, the average ratio of the sumof the methyl and aryl groups per silicon atom, in the polymer, rangesfrom about one to not more than two. Polymeric methyl aryl siliconescontaining an average 01' less than two total methyl and aryl groups foreach silicon atom are preferred. Products having good thermal resistanceand a wide variety oi applications are polymers containing an average ofapproximately 1 to approximately 1.4 total methyl and aryl groups persilicon atom. silicones having an average 01' less than one total methyland aryl roups per silicon atom also may be produced in accordance withthe present invention. The average ratio of methyl groups to aryl groupsfor each silicon atom may be varied as desired or as conditions mayrequire. For most applications of these new methyl aryl silicones Iprefer that the average number of methyl groups per silicon atom exceedthe average number of aryl groups per silicon atom.

The introduction of halogen atoms into the aryl nucleus of these methylaryl silicones imparts flame resistance to the end-products. Thus,whereas non-halogenated methyl phenyl silicone burns upon application ofa flame, the introduction of one halogen atom, specifically a chlorineatom, into the phenyl group renders the product less flammable.Similarly the introduction of two chlorine atoms into the phenyl groupimparts greater flame resistance than one chlorine atom. Such monoanddi-halo derivatives may not be wholly flameproof. Hence for optimumflame resistance it is advantageous to introduce at least three halogenatoms, e. g., chlorine atoms, into the phenyl group. Similarly, withother aryl derivatives I may introduce .any number of halogen atoms upto the limit of combining power of the particular nucleus. 1! desired,instead of introducing a single halogen such as chlorine into the arylnucleus, a mixture oi halogens, e. g., a mixture of chlorine andbromine, may be introduced therein.

The methyl aryl silicones of this invention ordinarily are resinous incharacter. In their flnal form as polymeric bodies they have theadvantage of thermal stability greater than that of the ordinary coatingand bonding agents. The partial condensation products or polymers aresoluble, thermoplastic bodies. They polymerize slowly upon theapplication of heat. As the heat-' ing is continued, their solubility inorganic solvents correspondingly decreases and they become harder atroom temperature. The polymeric materials have good electricalproperties. The highly polymerized bodies are unaffected by water, andthey are able to resist temperatures of the order of 300 C. forprolonged periods oi time without any great change in their physicalproperties. The highly polymerized bodies may be insoluble, orinfusible, or. insoluble and infusible resinous masses, depending uponthe particular starting components, the proportions thereof and theconditions of polymerization.

As these new methyl aryl silicones are free from many 0! the limitationsof the purely oranic substances, they may be used to advantage withinorganic fillers and flbers such as asbestos, mica, glass fiber, andthe like, to provide a composite insulation capable of withstandinhigher temperatures than would be possible with the use of organicbinders. This in turn permits the design of electrical machinery foroperation at higher temperatures.

To illustrate how compositions comprising the herein-described methylaryl silicones may be used in the field of insulation, the followingexamples are cited:

A liquid coating composition comprising partly polymerized methyl arylsilicone, e. g., methyl phenyl silicone, and a volatile solvent may beapplied to a metallic conductor such as copper 7 wire, which thereafteris heated to vaporize the solvent and to continue or complete thepolymerization of the silicone in situ. In manufacturing certain kindsof electrical cables it may be desirable to wrap the conductor with anorganic or an inorganic fibrous material such as asbestos, glass, cottonor paper before treating it with the solution. A further procedure is tocoat and at least partly impregnate the wrapped conductor with a methylaryl silicone, wind the thus insulated conductor into the desired coil,and then heat the wound coil to complete the polymerization of thesilicone. In the accompanying drawing Fig. i represents across-sectional view of a metallic conductor provided with insulationcomprising polymeric methyl aryl silicone; and Fig. 2 shows a similarview of a metallic conductor provided with insulation comprising anintimate association of fibrous material and a composition comprisingpolymeric methyl aryl silicone.

Sheet insulation may be prepared by treating woven or felted organic orinorganic fabrics or paper with compositions comprising a methyl arylsilicone. Sheet insulation also may be prepared by binding flakyinorganic substances with a methyl aryl silicone. For example, a methylaryl silicone, specifically methyl phenyl silicone, may be used in theproduction of laminated mica products comprising mica flakes cementedand bonded together with the silicone.

Self-supporting coherent films or sheets of clay such as bentonite maybe treated to advantage with compositions comprising a methyl arylsilicone. The silicone may be applied in melted or solution state. Inthe production of such sheet materials from bentonite, particles ofbentonite of ultramicroscopic size are employed, for example particleshaving a maximum diameter of 3000 A. (Angstrom) more specifically fromabout 500 A to about 2000 A. Fibers such as glass may be embedded in, orotherwise associated with, such clayey films or sheets and the compositematerial treated, for instance coated, with a methyl aryl silicone.These methyl aryl silicone-treated bentonite and bentonite-glass fiberflexible sheet materials may be used to particular advantage for hightemperature electrically insulating applications.

In addition to their use in the field of insulation, the methyl arylsilicones of this invention also may be used as protective coatings, forinstance as coatings for base members such as glass bulbs and otherarticles of manufacture which are, or may be, exposed to abnormal heatconditions or to hot flying particles. They also may be used as sealingcompositions, in the production of so-called resistance orsemi-conducting paints, and for other applications as described morefully in my copending applications Serial Nos. 287,787 and 296,819 withparticular reference to methyl silicones and halogenated aryl silicones.

In certain cases it may be desirable to copolymerize mixtures ofcompounds having a particular ratio of total methyl and aryl groups tosilicon in the molecule of each individual compound. This may be done,for example, by mixing suitable proportions of, say, methyl phenylsilicon chlorides containing an average of 1 total methyl and phenylgroups per silicon atom with methyl phenyl silicon chlorides containingan average of say, 1.8 total methyl and phenyl groups per silicon atom,hydrolyzing the mixture and dehydrating the resulting product. In othercases, the separately hydrolyzed products may be mixed and thereafterdehydrated. However, in such cases the components should be mixed beforecondensation and polymerization have advanced to the point where thebodies become incompatible. For other applications it may be de.-sirable to polymerize the individual silicones to solid form and thenmix and grind the materials together to obtain a composite mass. Inthese and other ways compositions comprising methyl aryl silicone havingproperties best adapted for a particular application may be produced.

The individual, co-polymerized, or mixed methyl aryl silicones of thisinvention may suitably be incorporated into other materials to modifythe properties of the latter. For example, they may be compounded withsubstances such as natural and synthetic rubber; tars, asphalts andpitches, more specific examples of which are wood tars, petroleumasphalts and vegetable pitches; natural resins such as wood rosin,copal, shellac, etc.; synthetic resins such as phenolaldehyde resins,urea-aldehyde resins, modified and unmodified alkyd resins, cumarresins, vinyl resins, esters of acrylic and methacrylic acids, etc.;cellulosic materials such as paper, inorganic and organic esters ofcellulose such as cellulose nitrate (pyroxylin), cellulose acetateincludingthe triacetate, cellulose propionate, cellulose butyrate, etc.,cellulose ethers such as methyl cellulose, ethyl cellulose, benzylcellulose, etc., as well as with various other organic plasticcompositions. In certain cases the hard, brittle polymers may bepulverized and used as fillers for substances such as above mentioned.In other cases, especially when the methyl aryl silicone is compatiblewith the substance with which it is to be incorporated, it may be in theform of a liquid or relatively soft polymer of low molecular weightprior to compounding with the substance to be modified.

These new methyl aryl silicones also may be compounded with variousother materials. For example, the hard, brittle polymers may beplasticized by the addition of suitable plasticizing agents, or thesilicones of lower softening point themselves may be used asplasticizers of other normally brittle substances.

The low molecular weight polymers herein described also may be dissolvedor dispersed in oils, such as linseed oil, Chinawood oil, perilla oil,soya bean oil, etc., alone or mixed with solvents, pigments,plasticizers, driers and other components of coating compositions toyield products which, when applied to a base member and air-dried orbaked, have a high degree of heat resistance.

Laminated products may be made by superimposing organic or inorganicfibrous sheet materials coated and impregnated with a methyl arylsilicone, and thereafter bonding the sheets together under heat andpressure. Molding compositions and molded articles also may be formedfrom these new silicones. If desired, filling materials such asasbestos, glass fibers, talc, quartz powder, wood flour, etc., may beincorporated into such compositions prior to molding. Shaped articlesare formed from such compositions under heat or under heat and pressurein accordance with practices now widely used in the plastics arts.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A composition of matter comprising methyl aryl silicone.

2. A composition of matter comprising methyl halo-aryl silicone.

. Methyl aryl silicone.

4. Methyl halo-aryl silicone.

. Polymeric methyl aryl silicone.

. Polymeric methyl halo-aryl silicone. Polymeric methyl phenyl silicone.

. Polymeric methyl chloro-phenyl silicone.

A composition of matter comprising a mixture of polymers of methyl arylsilicones.

10. A resinous composition comprising polymeric methyl aryl siliconewherein the average ratio of the sum of the methyl and aryl groups persilicon atom is not more than two.

11. A product comprising polymeric methyl halo-aryl silicone wherein theaverage ratio of the sum of the methyl and halo-aryl groups per siliconatom is not more than two.

12. A product comprising polymeric methyl phenyl silicone wherein theaverage ratio of the sum of the methyl and phenyl groups is less thantwo.

13. Polymeric methyl phenyl silicone wherein the average ratio of thesum of the methyl and phenyl groups per silicon atom is between one andtwo.

14. Polymeric methyl chloro-phenyl silicone wherein the average ratio ofthe sum of the methyl and chloro-phenyl groups per silicon atom isbetween one and two.

15. A liquid coating composition comprising a volatile solvent and apartly polymerized, soluble methyl aryl silicone.

16. An article of manufacture comprising a base member having thereon acoating comprising an insoluble polymeric methyl aryl silicone.

17. The method of preparing new chemical compounds which compriseshydrolyzing a mass containing a compound having the formulawhereAisanarylradicalandxisahalogen atom, and dehydrating the hydrolyzedproduct.

18. An article of manufacture comprising an inorganic sheet materialtreated with a composition comprising a polymeric methyl aryl silicone.

19. An article of manufacture comprising a sheet material formed ofcohering particles of bentonite, said sheet material being treated witha composition comprising a polymeric methyl aryl silicone.

20. An article of manufacture comprising an intimate association ofglass fibers and a composition comprising a polymeric methyl arylsilicone.

21. An article of manufacture comprising an intimate association ofglass fibers and a composition comprising a polymeric methyl haloarylsilicone.

22. An article of manufacture comprising an intimate assmlation ofasbestos and a composition comprising a polymeric methyl aryl silicone.

23. An insulated electrical conductor comprising a metallic conductorand insulation thereon comprising a polymeric methyl aryl silicone.

24. An electrical cable comprising a metallic conductor and insulationthereon comprising an intimate association of fibrous inorganic materialand a composition comprising a polymeric methyl aryl silicone.

25. An insulated electrical conductor comprising a metallic conductorand insulation thereon comprising glass fibers associated with acomposition comprising a polymeric methyl phenyl silicone.

26. An article having a surface provided with a coating comprising amethyl phenyl silicone in an insoluble, substantially completelypolymerized state.

27. A composition comprising a mixture containing an organic plasticcomposition and a polymeric methyl aryl silicone.

EUGENE G. ROCHOW.

